One hundred years of quantum physics

This year marks the 100th anniversary of Max Planck's creation of the quantum concept, an idea so revolutionary that it took nearly 30 years for scientists to develop it into the theory that has transformed the way scientists view reality. In this month's essay, Daniel Kleppner and Roman Jackiw recount how quantum theory, which they rate as "the most precisely tested and most successful theory in the history of science," came to be, how it changed the world, and how it might continue to evolve to make the dream of ultimate understanding of the universe come true.     

“三农问题”的新“三化”途径探讨

为了探讨中国“三农问题”的解决途径,笔者回顾和总结了国外农业发展的经验与新理念,以及中国的实践与探索,提出了“三农问题”可以通过优势农业集群化、农村产权市场化、农民新型城市化“三化”的途径来实践。以安徽省淮北市为例,介绍了“三化”理念与途径在《淮北市城乡一体化空间布局规划》的应用与实践,指出“三化”途径也是推进区域城乡一体化的重要手段与途径。但是,经归纳与推论得出的“三化”途径还需在中国的农村改革与实践中验证与修正。     

When do anomalies begin?

An anomaly in science is an observed fact that is difficult to explain in terms of the existing conceptual framework. Anomalies often point to the inadequacy of the current theory and herald a new one. It is argued here that certain scientific anomalies are recognized as anomalies only after they are given compelling explanations within a new conceptual framework. Before this recognition, the peculiar facts are taken as givens or are ignored in the old framework. Such a "retrorecognition" phenomenon reveals not only a significant feature of the process of scientific discovery but also an important aspect of human psychology.     

ECOLOGY: The Other H's

Fisheries scientists have long identified the factors implicated in salmon decline as the "four H's": hydropower dams, harvesting, habitat degradation, and hatchery misuse. According to a new plan by nine federal agencies, known as the "All-H Paper," improvements in the other three H's will provide benefits that are more certain and widespread than those from dam breaching. But addressing the other H's may be even more costly than breaching dams.     

Pathway databases: a case study in computational symbolic theories

A pathway database (DB) is a DB that describes biochemical pathways, reactions, and enzymes. The EcoCyc pathway DB (see http://ecocyc.org) describes the metabolic, transport, and genetic-regulatory networks of Escherichia coli. EcoCyc is an example of a computational symbolic theory, which is a DB that structures a scientific theory within a formal ontology so that it is available for computational analysis. It is argued that by encoding scientific theories in symbolic form, we open new realms of analysis and understanding for theories that would otherwise be too large and complex for scientists to reason with effectively.     

THE METAL CARBONYLS

When the metal carbonyls were first discovered, their properties were startling because they seemed to violate nearly all the previously recognized generalizations of chemistry. Even to-day the existence of the carbonyls is not particularly emphasized in elementary courses of chemistry because it is rather hard to reconcile them with the first presentations of the generalizations of chemistry. Nevertheless, as the student progresses deeper into the knowledge of chemistry it becomes desirable to include the knowledge of the carbonyls both because they become more comprehensible when viewed in the light of Werner's system of coordination and because they themselves contribute to the comprehension of the Werner theory. As long ago as 1931, Reiff in his discussion of cobalt nitrosyl carbonyl recognized the correlation between the effective atomic number and the volatility of carbonyls. A more recent study of charged Werner coordination complexes, that is, of complex ions, has shown a similar role of the effective atomic number. We are standing on fairly firm ground when we point out the correlation between E.A.N. and the volatility of the carbonyl complexes and the existence of complex ions. Be it noted that we have made no postulates as to the arrangement of the electrons in quantum levels. In the inert gases the outer principal quantum group is supposed always to contain eight electrons. In the carbonyls and other Werner complexes there is no compelling reason to suppose that the electrons in the coordinating layer, be this layer of eight, ten, twelve or sixteen electrons, are not all at the same energy level. Although we have confined our discussion almost exclusively to the property of volatility, the carbonyls are very interesting from the standpoint of several other properties, for example, magnetic susceptibility and dielectric constant. Enthusiasts in the interpretation of such properties try to draw conclusions as to the condition of the electrons, sometimes they become so dogmatic as to seem really.to believe in the actual existence of the condition they postulate. As Professor Smith said, "Theories come and theories go, but facts live on forever." The facts of chemistry are so multitudinous that we would be utterly helpless to use them had we not means of correlating them. Any postulates which reach beneath the surface of the directly observable to give a mechanism to correlate the facts are helpful. But a scientist without a sense of humor is pretty hopeless. Who in his right mind can regard as other than absurd the idea that an electron pair can simultaneously occupy positions in two atom shells to make up the supposedly necessary number in each atom? In fact, is not the electron itself a pretty ridiculous figment of the imagination? To be sure, we recognize the electron as a discrete entity with certain very definite properties, but in the light of comparison with any mechanism within our comprehension is not the electron perfectly impossible? By all means let us use a postulate which allows us to make a useful classification of facts, but never let us lose the sense to see how utterly ridiculous the postulate will look to one who has not like ourselves grown attached to it. We do not expect ever to discover the ultimate reason for things, but we do expect ever to make progress in correlating and classifying the facts which we have already discovered and shall continue to discover. Dogmatic belief in ridiculous postulates retards this progress.     

Recent Advances in Color Vision

Until a few years ago it was possible to account for nearly all the aspects of human color perception on the basis of the three-color theory, but such is no longer the case. This is largely due to improvements in the older methods of investigation and to the invention of new ones. Among the latter may be mentioned the microelectrode technique of Granit and the retinal direction effect of Stiles and Crawford. Modern requirements are met by a polychromatic theory, comprising 7 types of receptor, but there is no necessity for these to have such narrow spectral response curves as those exhibited by Granit's modulators. Modifications of the three- and four-color theories have been examined to see to what extent they can be made to fit in with experimental results. Particular notice has been taken of the possibility that there is polychromatism of the retinal receptors, but trichromatism of the nerve paths which connect these to the brain or even of the brain itself. The conclusion arrived at is that there must be polychromatism throughout the entire visual mechanism for color perception if a complete account is to be given of all the known facts.     

基于养生理念的“新中式”景观设计——以南京中医药大学景观改造为例

通过对"新中式"景观及养生理念的阐述,梳理了养生理念与自然环境之间的关系,提出了养生理念与"新中式"景观结合的思路。并以南京中医药大学景观改造为例,从结构布局与细部设计层面分别论述了基于养生理念的"新中式"风格的应用,旨在为"新中式"景观的发展提供新的思路与参考。     

Freezing

There is no first principles theory of freezing or melting, even for the simplest materials. The prediction of phase diagrams is an important first step in understanding the crystal-melt interface, crystallization near equilibrium, and nucleation. Recently, a new approximate theory for the freezing of classical liquids, known as the density functional theory, has been developed. The predictions of the theory are relatively accurate and its mathematical structure is simple enough to provide an attractive starting point for theories of more complex, dynamical phenomena.     

THE SOURCE OF SOLAR ENERGY

While I have wandered from the main subject of the sun, to consider the source of stellar energy, the two topics are so intimately related that their solutions are identical. I consider that I have demonstrated the reasonableness of Jeans's theory by the manner in which it seems to fit the observed facts. There is, as I can see, no important objection to the hypothesis. It is too much to hope that the foregoing analysis is rigidly complete, but I confidently believe that the main points are established and that further modification will consist in the clearing up of details. The application of astrophysics and atomic theory to a new field appears to have met with considerable success. In spite of this success, however, caution is necessary. The present position of the theory advocated in this paper is somewhat analogous to the place once held by the theory of Helmholtz-i.e., it is the only one sufficiently elastic to stretch over the region of known facts. Our knowledge is yet limited and, with our vision thus impaired, we can not predict the future. Some unforeseen event may upset our present hypothesis as completely as that of Helmholtz; we have built as securely as possible upon observation, and it remains for the future to test the accuracy of this or any other theory so established. In an attempt to discover a reasonable explanation of the origin and duration of the solar radiation, all possible sources of energy are examined. The following hypotheses are reviewed and discarded, the arguments against their validity being too well known to necessitate a review at this place; (1) Original Heat; (2) Chemical; (3) Gravitational, (a) Meteoric, (b) Contraction; (4) Radioactive.     

Body chemistry. Where dead men really do tell tales

Here at the "Body Farm," a research plot where human corpses are studied as they decompose, the corpses are teaching scientists much about how to reconstruct the manner and circumstances of unexplained deaths. In fact, new techniques developed at the site, officially known as the University of Tennessee, Knoxville's, Anthropological Research Facility, are already beginning to land criminals behind bars.     

Time-dependent processes in memory storage

These observations indicate that the long-lasting trace of an experience is not completely fixed, consolidated, or coded at the time of the experience. Consolidation requires time, and under at least some circumstances the processes of consolidation appear to be susceptible to a variety of influences- both facilitating and impairing- several hours after the experience. There must be, it seems, more than one kind of memory trace process (31). If permanent memory traces consolidate slowly over time, then other processes must provide a temporary basis for memory while consolidation is occurring. The evidence clearly indicates that trial-to-trial improvement, or learning, in animals cannot be based completely on permanent memory storage. Amnesia can be produced by electroshock and drugs even if the animals are given the treatment long after they have demonstrated "learning" of the task. Of particular interest is the finding that retention of the inhibitory avoidance response increases with time. In a sense this should be expected, for it has long been known (and ignored) that, within limits, learning is facilitated by increasing the interval between repeated trials (7, 30). Our result may be the simplest case of such an effect. Since the improvement in retention with time seemed not to be due solely to consolidation (as indicated by electroshock effects), it would seem that the "distribution of practice" effect, as it is typically designated, may be due in part to a time-dependent temporary memory storage process. In our work with animals we have found no analog of human immediate memory such as that required for repeating digits (or finishing sentences). Animals tested immediately on the task described above after a trial typically showed no evidence of memory. It could be that the poor performance is due to excessive fright, but the "distribution of practice effect" is also typically observed in learning experiments in which food reward is used rather than shock avoidance. Since the retention tasks require the animals to change their behavior in some way, it could well be that the growth of retention over the first few minutes after a trial is due to time dependent processes involved in the organization of processes necessary for changing behavior, in addition to those involved in temporary storage and retrieval. It is worth pointing out that there is evidence of an analogous process in human memory (32). A complex picture of memory storage is emerging. There may be three memory trace systems: one for immediate memory (and not studied in our laboratory); one for short-term memory which develops within a few seconds or minutes and lasts for several hours; and one which consolidates slowly and is relatively permanent. The nature of the durability of the longterm memory trace (that is, the nature and basis of forgetting) is a separate but important issue. There is increasing evidence and speculation (20, 21, 33) that memory storage requires a "tritrace" system, and our findings are at least consistent with such a view. If there are, as seems possible, at least three kinds of traces involved in memory storage, how are they related? Is permanent memory produced by activity of temporary traces (31), or are the trace systems relatively independent? Although available findings do not provide an answer to this question, there does seem to be increasing evidence that the systems are independent. Acquisition can occur, as we have seen, without permanent consolidation, and both short-term and long-term memory increase with time. All this evidence suggests (but obviously does not prove) that each experience triggers activity in each memory system. Each repeated training trial may, according to this view, potentiate short-term processes underlying acquisition while simultaneously enhancing independent underlying long-term consolidation. Obviously, acceptance of these conclusions will require additional research. If this view is substantially correct, it seems clear that any search for the engram or the basis of memory is not going to be successful. Recognition of the possibility that several independent processes may be involved at different stages of memory may help to organize the search. A careful examination of the time course of retention and memory trace consolidation, as well as examination of the bases of the effects of memory-impairing and memory-facilitating treatments, may help to guide the search. It is clear that a complete theory of memory storage must eventually provide an understanding of time-dependent processes in memory. In 1930 Lashley wrote (2), "The facts of both psychology and neurology show a degree of plasticity, of organization, and of adaptation and behavior which is far beyond any present possibility of explanation." Although this conclusion is still valid, the current surge of interest in memory storage offers hope that this conclusion may soon need to be modified.     

The Rockefeller Foundation and the green revolution, 1941–1956

High yielding agriculture in less-industrialized countries, the green revolution, has been both honored and criticized over the past twenty years. Supporters point to the increased food supplies produced with the new practices, but detractors argue that the new technologies are environmentally destructive, unsustainable, and socially inequitable. This paper explores the origins of high yielding agriculture in order better to understand how the arguments over sustainability and equity originated. The Rockefeller Foundation was an important agency in promoting the development of the new agricultural science. Its programs in Mexico and India, initiated in 1941 and 1956, were key building blocks in creating high yielding agricultural practices. The Foundation scientists saw rapid population growth as the main source of hunger and communist subversion. In order to alleviate hunger and instability, they created a strategy of agricultural development based on increased yields but paid no attention to the problem of distribution of harvested food. Sustainability was not recognized as a problem at the time Foundation scientists began their work. Indeed the technical successes of their programs prompted the development of concerns about sustainability. Equity of distribution was brought to the attention of the Foundation before it began its work, but the scientists paid no attention to the issue.     

PALEOCLIMATE: An Appealing Snowball Earth That's Still Hard to Swallow

The startling claim that Earth has frozen over from pole to pole for millions of years at a time, a hypothesis widely known as the "snowball Earth" scenario, has intrigued many earth scientists but as yet convinced few. But the theory, which would explain some previously inexplicable observations from the Neoproterozoic era 600 million to 700 million years ago, is gaining adherents. Last year, for example, most researchers agreed that one part of the sweeping hypothesis--the claim that glaciers once flowed into ice-covered tropical seas--is correct, even though this idea had been rebuffed for more than 30 years.     

中西人权观源流新探

本文从“三代人权论”谈起，指出人权学说有一个发生、发展和完善的过程。“人权”虽然是一个近代西方的概念，但是人权作为一种实存和理念无论在古代希腊和古代中国即己存在。中西人权观具有共同的特点，即都是建立在人性论、“自然论”基础之上，都反对君权专制和暴政。不过，中西人权观也有明显的区别，即西方人权观是与民主政治相结合的，而中国的人权观是与“王道”相结合的;西方人权观的核心是“人”，而中国人权观的核心是“民”;西方人权观与法制相结合，中国的人权观与人治相结合。具有现代性的第三代人权观则强调“人类人I权”，它既吸收了中西人权观的合理因素，又超越了传统的中西人权观。     

Innovation in industry and the diffusion of technology

The varied definitions used in the sources that have been discussed make any aggregate analysis difficult. A simple three-stage analysis of flows to, from, and within the firm was used to facilitate comparisons. Even so, each of the generalizations is drawn from relatively small and unrepresentative samples. Case studies may continue to be a source of ideas and hypotheses for further research, but do not appear to offer a means for deeper understanding of the innovation process. The retrospective nature of nearly all of the sources discussed probably means that the process has been viewed as much more rational and well-ordered than it is in fact. This failing is partially overcome in firsthand accounts such as those of Suites and Bueche (63) and Frey and Goldman (64). Each of these accounts involves a successful innovation according to technical or commercial criteria, or both. However, many of the characteristics of innovations that have failed commercially (10) appear to be similar to those of successful cases. The few longitudinal studies, and studies comparing more and less successful cases, do support the main conclusions drawn above (10, 32, 38). More serious problems are raised by the distinctly nonrepresentative nature of the samples used. There are few cases (17, 33, 65) in which the contributions of more than one organization, or details of interactions over a significant period of time, are discussed. There is a wide variation in the importance of the innovations included, ranging from those affecting the economy as a whole to cases involving production in a single firm, albeit with significant commercial results (66). In addition to questions of comparability and sampling, a central problem for further research on innovation will be to devise an operational model to account for interfirm and interindustry differences. Polar definitions used in past studies, "high technology" and "mature industry," for example, are insufficient. One possibility is to use the strategy for growth or competition evident in a firm or an industry, such as sales maximization (automotive), cost minimization (transportation, communications), performance maximization (aircraft, chemicals), or control of materials resources (mining, petroleum), as a basis for drawing distinctions (67). For example, in an industry that seeks to maximize sales, one would expect innovations that would be highly visible to consumers to be developed rapidly (68). In a cost-minimizing situation, production, as opposed to product technology, would be a major source of uncertainty, while the reverse might be the case in a performance-maximizing situation. Greater uncertainty arising from technical sources would imply greater sophistication in effective firms' product planning approaches, while a more stable technology would imply greater sophistication in market research and market-oriented strategies for innovation, and so forth. Much more work is needed along these lines if outcomes of interventions in the innovative process are to be predicted with any accuracy. Some implications for providing incentives and reducing barriers do seem clear from the work to date. Effective directions for federal action lie in strategies such as creating new markets through purchases or procurement policies; aggregating or focusing markets through regulation and other means; providing for market entry by contracts to smaller firms, venture capital, stronger patent protection, and so on; and providing for mobility and informal contacts within the technical community. Technology "push" strategies (such as tax incentives) to increase most research spending, prizes for new technology, and documentation and information retrieval systems would probably be less important in stimulating innovation. Definitive answers will require the most difficult kind of research-experiments in the field. Since the interventions required are difficult and expensive in most cases, they will not be under the researcher's control. Nor will the effect of policy changes be visible over a short period. Thus it seems imperative to take advantage of interventions that occur fortuitously to construct "quasi-experiments" (69) with as great a degree of control over other factors as possible. For example, have recent changes in policy regarding federally held patents increased the commercial use of these patents? Have changes in the capital gains laws retarded the development and growth of "spin-off" enterprises? Has the identification of technology gaps (3) and competitive opportunities stimulated innovation? The effects of such actions on technical innovation could be carefully observed with a modest but sustained research effort, which promises to yield valuable information beyond that available from largely historical sources.     

Zonal centrifuges and other separation systems

This discussion has included only a partial list of the systems now under development at Oak Ridge as part of the feasibility studies for the Molecular Anatomy Program. It is evident that we are still in the "Robert Goddard" phase of this work. It may not be premature, however, to suggest several conclusions.Biomedical scientists are discouraged on discovering that developmental efforts cost more, by one or two orders of magnitude, than pure research. In part this is because the full cost of development is generally shown, while in pure research some of the costs may be hidden, or the funds supplied by several sources. Regardless of the reason, the fact remains that development is expensive, as is well understood in nuclear physics and space science. The role and mission of the large national laboratories, and the kinds of research that should be done in them, have been discussed by Weinberg (63). The studies described here were in part stimulated by his ideas. We have been unable to find an environment outside a large national laboratory where a program like the Molecular Anatomy Program could be undertaken at the present rate. It appears that programs which attempt to make use of the multidisciplinary approach characteristic of national laboratories should be carefully designed and should evolve experimentally. There is less chance of success when a program is an administrative invention than when it evolves from scientific invention and discovery. It has been pointed out (64) that most program decisions in science are secret decisions in the sense that the scientific community as a whole does not participate in them. If a choice is to be made at some future time between large-scale expenditures for exploring space, for developing new weapons systems, for constructing new accelerators, for designing large reactors, or for systematically developing methods to explore the molecular basis of human disease, then we will need sufficient information to evaluate each alternative fully, and the information should be generally available. It appears desirable, therefore, to allow the Molecular Anatomy Program to proceed to a point where the full range of its contributions and its inherent limitations may be seen. A rational choice may then be made.     

Paleontology. New feathered dino firms up bird links

Last week, Chinese scientists presented evidence from a new specimen dug up in Liaoning Province that they say strengthens the case for the bird-dinosaur link. The finding, one of several fossils displayed at a meeting here, is the third known specimen of a strange creature known as Caudipteryx which, unlike any other known dinosaur fossil, shows the unmistakable imprints of feathers. The researcher who described the new specimen at the meeting has identified 16 characteristics of the new fossil that are more similar to dinosaurs than to early birds, reinforcing the views of most Western scientists.     

Regular Disjunction-Free Default Theories

In this paper, the class of regular disjunction-free default theories is introduced and investigated. A transformation from regular default theories to normal default theories is established. The initial theory and the transformed theory have the same extensions when restricted to old variables. Hence, regular default theories enjoy some similar properties (e.g., existence of extensions, semi-monotonicity) as normal default theories. Then, a new algorithm for credulous reasoning of regular theories is developed. This algorithm runs in a time not more than O(1.45^n), where n is the number of defaults. In case of regular prerequisite-free or semi-2CNF default theories, the credulous reasoning can be solved in polynomial time. However, credulous reasoning for semi-Horn default theories is shown to be NP-complete although it is tractable for Horn default theories. Moreover, skeptical reasoning for regular unary default theories is co-NP-complete.     

The pure-science ideal and democratic culture

These early experiences of pure scientists will have an unmistakable ring of familiarity to anyone familiar with the current situation. Charles Sanders Peirce, with characteristic insight, had stated the fundamental dilemma of the pure scientist operating within a democratic framework. How can one ask the public to provide support, much less facilities, for the intellectual gratification of one select group? A part of the answer, of course, is simply that one cannot. As long as a group is dependent upon public support it must seek some means of contact with the values of the enveloping society, and the moment it does this it departs in some measure from the ideal purity. The schizophrenic attitude described by Dubos therefore became a professional necessity as soon as the new ideal was adopted. Since the time of Gould, scientists have been able to tell each other that the man who based science's claim to support on grounds of immediate practical utility was "no loyal follower and true friend of science" and, at the same time, to trust that the popularizers and technicians would convey a different message to the public. On the whole, they have not been disappointed in their expectation, and there has been little need for them to go beyond the standard formula : Utility is not to be a test of scientific work, but all knowledge will ultimately prove useful. Since the continued existence of scientists in this society depends upon the believability of that vague claim, there is little likelihood hood that the schizophrenia will disappear.